This invention concerns holding fixtures and methods for testing valve assemblies which requires the valve assemblies to be threaded into a fixture housing block, as is often done with so-called hydraulic and air "cartridge" valves. Such cartridge valves have a threaded stem, which typically project from a housing enclosing an electrical coil operator. Other types of cartridge valve operators are also used. A wrenching contour is formed on the valve stem which is engaged with a wrench and rotated manually to advance the threaded section of the valve stem into a threaded bore in the fixture housing block.
An O-ring seal is located against a shoulder located beneath the wrenching contour and when compressed against a surrounding surface seals the valve assembly in the fixture as the valve assembly is seated in the threaded bore.
When conducting a test, the operator housing is typically removed and the valve threaded into the threaded bore in the test block and tightened using a wrench. The operator housing then must be reinstalled in order to test the valve function.
This procedure has the disadvantage that when the valve is removed from the test block, the O-ring seal is often damaged as the threads of the valve stem are rotated within the O-ring.
Furthermore, the test procedure itself is relatively slow due to the need for manual assembly and disassembly of the operator housing and threading of the valve assembly into and out of the housing block.
Accordingly, it is an object of the present invention to provide a method and fixture which simplifies the testing of valve assemblies which are required to be threaded into a housing block.